MRI-Compatible Steerable Surgical Needle Using Piezoelectric Actuators
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Solution Overview
Problem
Current steerable surgical needles used in procedures like prostate biopsy and brachytherapy face challenges with inaccuracy due to the incompatibility with MRI machines and the need for precise needle placement, leading to potential misdiagnoses and suboptimal treatment outcomes.
Innovation Solution
A steerable surgical apparatus with nonmagnetic piezoelectric actuators and fiducial markers, designed to operate within an MRI machine bore, allowing for precise control of needle rotation, translation, and bending, enabling accurate targeting and navigation during procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If traditional electromagnetic servomotor actuators are used in robotic systems, then automation and precision are improved, but compatibility with MRI machines deteriorates due to ferrous material interference with magnetic fields
Solution Approach 1:
The patent replaces electromagnetic servomotor actuators with nonmagnetic piezoelectric actuators that do not interfere with MRI magnetic fields. The piezoelectric materials (such as PTFE, PEEK, or ceramic materials) provide precise actuation without containing ferrous elements, thus eliminating the conflict between automation and MRI compatibility.
Solution Approach 2:
The patent changes the material composition parameter of the actuator from ferrous-based electromagnetic materials to nonmagnetic piezoelectric materials. This parameter change allows the system to maintain automated control while becoming compatible with MRI environments, as the piezoelectric materials do not respond to or interfere with magnetic fields.
2Ease of operation
If passive devices are used for needle insertion, then procedural simplicity is maintained, but needle actuation capability deteriorates leading to extended procedural times
Solution Approach 1:
The patent implements self-service through automated piezoelectric actuation of the needle, eliminating the need for manual manipulation while reducing procedural time. The piezoelectric actuators automatically perform the needle insertion and positioning actions that would otherwise require extended manual intervention, thus improving productivity without complicating the overall procedure.
3Ease of operation
If ultrasound guidance is used for needle insertion, then accessibility is improved, but image quality and needle visibility deteriorate due to noise and tissue alignment requirements
Solution Approach 1:
The patent introduces MRI imaging as an intermediary system that provides superior image quality and needle visibility compared to ultrasound. The MRI scanner serves as the mediator that delivers high-precision anatomical imaging and real-time needle tracking without the noise and alignment limitations of ultrasound, while maintaining the accessibility benefits of minimally invasive procedures.
4Strength
If rigid needles are used for brachytherapy, then structural strength is maintained, but steering capability and trajectory control deteriorate
Solution Approach 1:
The patent transforms the needle from a rigid static structure to a dynamically controllable steerable structure. The needle incorporates flexible sections with embedded piezoelectric actuators that allow real-time adjustment of the needle's curvature and orientation while maintaining sufficient structural strength. This dynamic capability enables precise trajectory control for targeted brachytherapy seed placement.
Solution Approach 2:
The patent segments the needle into multiple sections with varying degrees of flexibility and strength. The needle comprises a rigid proximal section for insertion and flexible distal sections for steering, with internal tendons and actuators providing controlled flexibility. This segmentation allows different portions of the needle to perform different functions - strength where needed and steering capability where required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances diagnostic accuracy and treatment efficacy by allowing for precise needle placement and movement within the MRI environment, improving detection rates and reducing procedural time and complications.
Implementation Method 1
A steerable surgical apparatus with nonmagnetic piezoelectric actuators and fiducial markers, designed to operate within an MRI machine bore, allowing for precise control of needle rotation, translation, and bending
Data Source
AI summary
A steerable surgical apparatus comprises a steerable surgical tubular needle, a needle manipulation apparatus with multiple actuators (permitting adjustment of needle rotation, translation, and bending), fiducial markers affixed to the needle manipulation apparatus, encoders configured to sense movements initiated by actuators, and a control unit. The needle manipulation apparatus is devoid of ferrous materials, and is configured to be placed and operated within an MRI machine bore. The control unit determines position and orientation for: (i) the needle manipulation apparatus relative to the MRI machine bore, such as by MRI imaging of the fiducial markers, and (ii) the needle inserted into a patient within the MRI machine bore, such as by kinematics utilizing signals of the encoders.